Increased Limestone Mineral Addition in Cement the
Affect on Chloride Ion Ingress of Concrete – A Literature
Review
B T (Tom) Benn, Adelaide Brighton Cement Ltd;
Associate Prof Daksh Baweja, University of Technology Sydney;
Prof Julie E Mills, University of South Australia;
Introduction
In this paper a review of current knowledge of chloride ion penetration into concrete made with Type
GP cement containing increased levels of mineral addition is presented. The review forms the
background to a proposed research program at the University of South Australia. The research will
include the incorporation of supplementary cementitious materials (SCM) as a replacement for the
cement, as these materials are well documented as improving the durability of concrete. In 2010 the
cement standard in Australia, AS 3972 (2010) was revised to allow a number of changes including an
increase to the maximum level of mineral addition to 7.5%. Mineral additions are defined in the
standard as limestone, fly ash or ground granulated blastfurnace slag (GGBFS) or combinations of
these materials. In addition cement kiln dust (CKD) can be incorporated as part of the mineral
additions up a maximum of five percent, denoted in the standard as minor additional constituents.
The paper will briefly summarise the fresh and hardened properties of concrete made with Type GP
cement as defined in Australian Standard AS 3972 (2010) and similar international cements
containing up to five percent limestone mineral addition
The paper will concentrate particularly on chloride ion ingress. Chloride ions penetrate concrete
through the mechanisms of diffusion, capillary absorption and hydrostatic pressure; these will be
discussed in detail. The potential of concrete to resist chloride ingress can be measured, directly or
indirectly but the test methods are not discussed in this paper. Published data will be assessed to
establish if there is sufficient evidence to conclude what effect increased levels of mineral addition
have on the rate of chloride ion ingress. The literature review will also identify gaps in available data,
e.g. use of cement kiln dust, that could be investigated as part of the research program.
Background
In 1991the Australian cement standard, “Portland and blended cements” (AS 3972-1991) allowed the
inclusion of up to five percent mineral additions, which were defined as limestone, fly ash or ground
granulated iron blastfurnace slag or combinations of these materials. In 2007 the Cement Technical
Committee of the Cement Concrete & Aggregates Australia (CCAA) commenced an investigation
program to assess the impact of increasing the limestone mineral addition to 10%. Several trials were
carried out independently at eight cement manufacturing plants and tested in the respective company
laboratories for compliance to AS 3972 – 1997.
The results obtained culminated in 2010 in a total revision of the cement standard, published as AS
3972 (2010) “General Purpose and blended cements”. In this revision the allowable mineral addition,
fly ash, GGBFS, limestone or combinations, was increased from 5% to 7.5% for all cement types in
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Australia. In addition, cement kiln dust, defined as a “minor additional constituent” was allowed at
levels up to a maximum of five percent of the total mineral addition. In Australia blended cement is
defined as having SCM content of greater than 7.5%. In Europe when supplementary cementitious
materials are used at levels greater than 5% the cements are generally referred to as CEM II –
Portland-composite cements (EN 197-1, 2000) and in the United States as blended hydraulic cements
(ASTM C595, 2012). In Australia the new General purpose limestone cement, Type GL, is defined as
cement with limestone contents of between 8% and 20%. This is different to the European practice
where cements with limestone mineral addition greater than five percent but less than 35% are
generally called CEM II - Portland limestone cements (EN 197-1, 2000).
Currently, under the auspices of the Cement Committee of Australian Standards Organisation, an
industry wide project is underway to produce technical data on fresh, hardened and durability
properties of concrete made with cements containing limestone additions of between 7.5% and 13%.
It is expected that this work will be completed in the second half of 2013.
The paper will briefly summarise some of the published data on the fresh and hardened properties of
concrete made with Type GP cement as defined in AS 3972 (2010) and similar international cements
containing up to five percent limestone mineral addition
The paper will consider in some detail the mechanisms of chloride ingress including diffusion,
capillary absorption and hydrostatic pressure however the different test methods of measuring
chloride ingress are not discussed in this paper. Published data will be assessed to establish if there is
sufficient evidence to conclude what effect increased levels of mineral addition have on the rate of
chloride ion ingress. The literature review will also identify gaps in available data that could be
investigated as part of the research program.
Materials
Cement
Australia adopted the inclusion of up to five percent mineral additions in 1991 (AS 3972-1991) and
the revision to the standard in 2010 increased this limit to 7.5%. The initial addition of mineral
additions, in 1991, was somewhat later than many other countries including most of Europe (early
80’s), Canada (CAN/CSA A5-1983) and South Africa (SABS 471-1971 amended 1982). The USA,
however, did not allow limestone additions until a revision of ASTM C150 in 2005.
The cement properties detailed in Table 1 indicate that Type GP cement (AS 3972, 2010), previously
known as Ordinary or Normal Portland cement, is the equivalent to CEM I 32.5N (EN 197-1, 2000)
and Type I (ASTM C150, 2007). The CEM I 42.5N cement although defined by EN 197-1 as an
ordinary early strength cement, it is more closely aligned to the AS 3972 Type HE cement and the
ATSM C 150 Type III cement. It must be noted that the Australian standard is now a performance
based standard while the ASTM is prescriptive and the EN standard can be considered somewhere inbetween.
Prior to the draft of the European code ENV 197-1 (1992), some European countries had already
allowed the use of limestone additions greater than five percent. According to Schmidt (1992),
Heidelberg Cement has produced limestone cement, containing 20% limestone, since 1965 and
France has produced limestone cements from the 1970’s. The ENV 197-1(1992) standard allowed
limestone additions of up to 35%, but accommodated these cement as a separate category called
“Portland limestone cements”.
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Table 1: Comparison of Cement requirements from Standards (AS 3792, 2010; EN 197-1, 2000
& ASTM C 150-2007)
Property
Units
Type GP
(AS 3972)
7.5 max
CEM I - 32.5N
(EN 197-1)
5 max
Mineral addition
%
Minor additional
constituents
%
Initial setting time
CEM I - 42.5N
(EN 197-1)
5 max
Type I
(ASTM C 150)
5 max
Considered a mineral addition
minutes
5%
max of mineral
addition
≥ 45
≥ 75
≥ 75
≥ 45
Final setting time
hours
<6
not specified
not specified
≤ 6.25
Soundness
mm
MgO
%
≤ 10
(Le Chatelier)
≤ 5.0
≤ 10
(Le Chatelier)
≤ 5.0
≤ 0.80
(autoclave expansion)
≤ 6.0
Chloride ion content
%
≤5
(Le Chatelier)
< 4.5
(in clinker)
≤ 0.10
≤ 0.10
≤ 0.10
SO3 content
%
≤ 3.5
≤ 3.5
≤ 3.5
Loss on ignition
%
not specified
≤ 5.0
≤ 5.0
≤ 3.0 (C3A < 8%)
≤ 3.5 (C3A > 8%)
≤ 3.0
Insoluble residue
%
not specified
≤ 3.5
≤ 3.5
≤ 0.75
2-days
MPa
not specified
not specified
≥ 10.0
not specified
3-days
MPa
not specified
not specified
not specified
7-days
MPa
MPa
≥ 16.0
(ISO prisms)
≥ 32.5 ≤ 52.5
(ISO prisms)
not specified
28-days
≥ 35
(ISO prisms)
≥ 45
(ISO prisms)
12.0
(50 mm cubes)
19.0
(50 mm cubes)
28.0 optional
(50 mm cubes)
Compressive strength
≥ 42.5 ≤ 62.5
(ISO prisms)
Limestone
Although fly ash and ground granulated blastfurnace iron slag can be used as mineral additions, the
most common material used is limestone as it is the most economical and easiest material for the
majority of cement manufacturers to handle. The quality of the limestone used for mineral addition at
the cement mill is specified by the various national cement standards. In AS 3972 (2010), limestone
must meet the following requirements, which were based on and are very similar to EN 197-1 (2000):
•
The limestone must be a natural inorganic mineral material.
•
It shall contain not less than 75% by mass of CaO3.
•
If the CaO3 content is between 75% and 80% the material is acceptable provided:
The clay content determined using the methylene blue test is less than 1.20%.
The total organic carbon content does not exceed 0.50% by mass.
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•
If the CaO3 content is 80% or greater no additional testing is required.
The Canadian Standard CSA A3001 (2008) has a minimum limit on the CaO3 of 75% in the limestone
and ASTM C 150 (2007) has a requirement of at least 70% by mass of the CaO3.
Cement Kiln Dust
The dust created and extracted from the kiln, during the burning process is referred to as cement kiln
dust (CKD), also sometimes called by-pass dust. This can constitute as much as 20% by weight of the
clinker, but is more typically 7% to 15% in dry kiln operations. The two designations noted above
usually refer to where in the clinker manufacturing process the material is collected. The collection
points are usually exhaust gas dust control devices such as cyclones, electrostatic precipitators and
bag-house dust collectors. CKD is normally removed from the clinker manufacturing process because
it can cause one or more of the following problems (Holderbank 1999):
•
Build-ups and rings in the kiln and/or preheater, due to a build up of chlorine, sulphur and
alkalis.
•
Abnormal setting characteristics and strength development in the cement.
•
High chloride content in the cement contributing to potentially increased chloride levels in
concrete.
•
Cracking of concrete, due to an increased propensity for alkali silica reaction if reactive
aggregates are used in combination with cement containing high alkali levels.
Even though CKD is removed from the process and is considered a waste, it can be used in various
ways. These include recycling into the kiln as part of the raw feed, provided that regular testing
indicates that it does not contain high levels of chlorides and alkalis. A survey by the Portland Cement
Association in 2006 (Adaska and Taubert 2008) found that nearly 50% of the CKD in the United
States was returned to the kiln. CKD can also be added to cement either at the milling stage or
blending with the cement after milling. Daugherty and Funnell (1983) showed that up to 10% of
interground CKD had little influence on concrete set times and shrinkage. They however found that
effects on strength were variable due to the variability in the dust composition. Studies by Bhatty
(1983, 1984a-c &1986) showed that if CKD was used as a replacement for clinker then the effect was
decreased strength, which was attributed to the alkalis in the CKD, increased water demand in the
concrete and retarded setting times. However, the negative effect of the alkalis was negated by using
fly ash and/or slag. If CKD is high in chlorides, alkalis and other chemicals that may be deleterious to
the use of cement in concrete, it is currently sent to landfill. Changes in the Australian cement
standard are aimed at encouraging the potential use of CKD whilst maintaining cement quality and
performance, and reducing landfill waste.
Supplementary Cementitious Materials
Both fly ash and GGBFS are well established as supplementary cementitious materials (Coal
Combustion Products Handbook 2007, p.206; Day 1999, p.245; Neville 1995, p.654; Fulton 1994,
p.6). The use of fly ash and GGBFS in concrete has several advantages including:
•
Improved workability due to their influence on fine aggregate grading,
•
Better cohesiveness and pumpability,
•
Significant and continuous compressive strength growth after 28-days,
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•
Reduction in the potential for alkali silica reaction if there are reactive aggregates in the concrete,
•
Reduction in concrete drying shrinkage with fly ash and potentially reduced shrinkage with
GGBFS where the properties of the current method of determining concrete drying shrinkage
(AS1012 Part 13) are properly evaluated,
•
Reduced heat of hydration,
•
Reduced permeability and chloride ion penetration and
•
Better resistance to chemical attack, including sulphates attack.
There are, however, some important disadvantages (Coal Combustion Products Handbook 2007,
p.206; Day 1999, p.244; Neville 1995, p.656; Fulton 1994, p.6) that must also be mentioned when
using SCM:
•
Longer concrete set times depending on the level of cement replacement,
•
Lower early strengths that may affect formwork stripping times,
•
Entrainment of air may be more difficult depending on the carbon content of fly ash, and
•
Undesired changes in fresh concrete properties where proper proportioning of SCM in concrete is
not carried out.
It is the advantages of improved impermeability and resistance to chemical attack that are of
particular interest in this research.
Properties of Cements Containing Limestone and Their Influence
on Concrete
Researchers have reported on limestone cements manufactured by post blending finely milled
limestone with cement or intergrinding limestone with clinker at cement manufacturing plants as well
as when fine limestone is added during batching at the concrete plant. The practice in Australia is to
intergrind these materials and as such, this is the focus of investigation in this paper. Voglis et al.
(2005) found that to achieve a similar compressive strength in concrete, the limestone cement
required a wider particle size distribution than the straight Portland cement. Tsivilis et al. (2002)
determined that within cement produced, the coarse fraction tended to be clinker and the fine fraction
the limestone.
There is still debate as to whether this very fine limestone is chemically reactive. Research by Soroka
and Setter (1997) indicated that although the reactivity is limited it can be influenced by grinding
more finely. This reactivity can be further influenced by sulphate content according to Campiteli and
Florindo (1990) who found that with increased limestone additions, the optimum sulphate level
decreased in both coarse and fine cements. Tsivilis et al. (1999a) reported that by increasing the
tricalcium aluminate (C3A) and reducing the tricalcium silicate (C3S) levels in clinker the compressive
strength at all ages increased, irrespective of the limestone replacement level between 10% and 35%.
For cements with up to 5% limestone addition, researchers reported an increase in the early strength
in concrete due to improved particle packing (Sprung and Siebel 1991). The increased early hydration
reported by Bonavetti et al. (2003) was thought to be due to the formation of nucleation sites that
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initiate hydration while Vogilis et al. (2005) ascribed it to the early formation of calcium
carboaluminates.
With respect to concrete, Matthews (1994) found that for the same slump the water to cement (w/c)
ratio needed to increase by 0.01 for limestone additions up to 5% and by a further 0.01 when
increased from 5% to 25%. However, Schmidt (1993) in a separate study using cement from a
different source reported that the water demand for concrete could be reduced for limestone cement
concrete. The compressive strength results of the CCAA investigation reported by Benn and Thomas
(2012), with limestone mineral addition of 10% are shown in Figure 1. The results of various grades
of concrete, made and tested in different laboratories, have been compared as a percentage of the
corresponding control mix, which contained 5% limestone mineral addition, and indicate that for
strengths up to 91-days all were within 90% of the control.
Figure 1: Compressive strengths of various grades of concrete as a percentage of the control
mix – CCAA investigation (Benn & Thomas, 2012)
The results in Figure 1 and results reported in the-state-of-the-art report by Hooton, Nokken &
Thomas (2007) supported the statement by Tsivilis et al. (1999a, page 115)
‘… that the appropriate choice of clinker quality, limestone quality, percentage limestone content
and cement fineness can lead to the production of a limestone cement with the desired properties’.
In general, the literature indicates that the initial set time of concrete decreased as the limestone
content was increased but that the final setting times increased. Heikal, El-Didamony and Morsy
(2000) reported that this was due to the effect of particle packing and the carboaluminate reaction.
Thomas and Hooton (2010) reported no discernable difference (±15%) in set times in field trials
where the cement, from the same manufacturing plant, with 12% limestone and no limestone
additions was used. As indicated in Figure 2 below, Benn and Thomas (2012) reported that the set
times of the eight Australian concrete trials, with limestone mineral additions of nominally 10%, were
within ±10% of the control.
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Figure 2: Set time of various grades of concrete as a percentage of the control mix – CCAA
Investigation (Benn & Thomas, 2012)
Alunno-Rossetti and Curcio (1997) reported that the rate of shrinkage and total shrinkage after one
year was similar for comparable concrete made with Portland cement and limestone cement from the
same plant. Dhir et al. (2007) also reported lower shrinkage for cement blended, not interground, with
limestone for blends up to 45 % limestone.
Figure 3: Concrete shrinkage at 28 and 56 days of various grades of concrete as a percentage of
the control mix – CCAA Investigation (Benn & Thomas, 2012)
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In the CCAA investigation (2009) the shrinkage of the various grades of concrete made with
limestone mineral addition of nominally 10% was measured by seven of the eight participating sites.
Figure 3(Benn & Thomas, 2012) shows the results which at 28 days were between 95% to 102% of
the control mix while the 56 day results were between 90% and 107% of control.
Sulphate resistance of cement paste in Australia, unlike other countries that specify maximum
tricalcium aluminates (C3A) levels, is based on performance. AS 3972 (2010) specifies that to be
sulphate resistant the expansion after 16 weeks exposure, to a standard sodium sulphate solution, must
not exceed 750 microstrain on any single results tested in a single laboratory. While not all Australian
manufacturers of Type GP cement claim that their Type GP cement will satisfy the Type SR
requirements the results obtained in the CCAA investigation (2007) indicated that when the
limestone mineral addition was increased to 10% at least 40% of the Type GP cements tested satisfied
the AS 3792 requirements.
Influence of Mineral Addition and CKD on Chloride Levels in Binder
and Concrete
Durability Related Issues
Of all the aspects that need to be taken into account when considering what is important for long term
durability, one generally accepted criterion is that concrete must be able to resist movement of fluids,
liquids and gasses, or deleterious substances such as chlorides and sulphates, through the cement/sand
matrix. Of these, chlorides are considered to be one of the most deleterious as they cause steel
corrosion in concrete, which in turn has a direct effect on durability and service life of a structure.
Chloride ions break down the passive layer around the reinforcing by activating the surface of the
reinforcing steel to form an anode, thus allowing potential for corrosion to increase in the presence of
moisture and air. Chlorides can be present in the constituents of the concrete or can ingress from
external sources. A significant amount of research has been done on chloride induced corrosion of
steel in concrete (CCAA, 2009).
Mechanisms of chloride ingress
There are essentially four modes of chloride ion transport (Hamilton, Boyd and Vivas 2007) through
concrete but often more than one mechanism is involved at any one time as summarised in Table 2.
The main modes (CCAA 2009; Hamilton, Boyd & Vivas 2007; Standish, Hooton & Thomas 1997)
are:
•
Diffusion – transfer of mass free ions in the pore solution from high concentration to low
concentration regions.
•
Capillary absorption – when moisture, perhaps laden with chloride ions, encounters the dry
surface of the concrete, it will be drawn into the pores by capillary suction, this often happens
where wetting and drying cycles are present.
•
Evaporative transport (also called wicking) – similar to absorption but where one surface is airexposed resulting in the moisture containing the chloride ions to be drawn from the wet surface to
the dry surface.
•
Hydrostatic pressure or permeation – where the hydraulic pressure on one side of the concrete
forces the liquid, containing the chloride ions, through the concrete matrix.
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Table 2: Chloride ion transport modes for various exposures (from CCAA, 2009)
Exposure
Type of structure
Primary chloride transport mode
Submerged
Substructure below low tide
Diffusion
Basement exterior walls or transport
tunnel liners below low tide. Liquid
containing structures
Permeation, diffusion and possibility
wick action
Tidal
Substructures and superstructures in
tidal one.
Capillary absorption and diffusion
Splash and
Superstructures above high tide in
the open sea.
Capillary absorption and diffusion
(also carbonation)
Land based structures in coastal area
or superstructures above high tide in
river estuary or body of water in
coastal area.
Capillary absorption (also
carbonation)
spray
Coastal
Of these transport mechanisms diffusion is the principal method of chloride ingress into concrete
(Stanish, Hooton & Thomas 1997) and is often modelled using Fick’s Laws. It must be noted that
chlorides are not passing through a homogeneous solution but a porous matrix consisting of both
liquids and solids. The solids can partially immobilize the chloride ions due to both chemical and
physical adsorption which leads to reduced rates of diffusion (Stanish, Hooton & Thomas 1997).
Other factors that influence the chloride diffusion include (Hamilton, Boyd & Vivas 2007; Standish,
Hooton & Thomas 1997) the water/cement ratio, the degree of hydration of the concrete, the use of
supplementary cementitious materials and amount of C3A in the cement.
Capillary absorption is not uncommon and many structures such as bridge columns and building
façades, particularly along the coast, are subject to wetting and drying cycles. The absorption is
affected by the viscosity, density and surface tension of the liquid as well as the radius, tortuosity and
continuity of the capillaries (CCAA, Chloride report 2009). Therefore the amount of liquid absorbed,
usually small, and the depth of penetration is governed by both time and rate of absorption.
Tsivilis et al. have reported, in several papers, on the permeability of concrete made with limestone
cement. It was concluded that:
•
The porosity of concrete made with limestone cements that have contained up to 15% limestone
was largely unaffected (Tsivilis et al. 2003), but porosity increases at higher limestone inclusions,
•
Limestone cement concretes compared favourably with Portland (Type GP) concrete or as stated
by Tsivilis et al. have ‘competitive concrete properties and improve the durability of the
concrete’. (Tsivilis et al. 2002, page 337), and
•
The quality and composition of both clinker and limestone impact on the permeability of the
concrete (Tsivilis et al. 1999a).
Tsivilis et al. (2000) tested grades of concrete at different limestone levels, with different w/c ratios
using ASTM C1202, the Rapid Chloride Permeability Test (RCPT). They concluded that limestone
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cements, containing up to 20% limestone addition, did not significantly affect the rate of chloride
ingress. However, the concrete made with limestone cements containing 35% limestone, even with a
reduced w/c ratio, exhibited higher rates of chloride penetration, indicating a potential of increased
permeability as indicated in Table 3.
Table 3: Effect of limestone additions on the “chloride permeability’ of concrete (Tsivilis et al.
2000)
Property
Percentage limestone
0
10
15
20
35
Fineness (m2/kg)
260
340
366
470
530
Mortar: 28 day strength (MPa)
51.1
47.9
48.5
48.1
32.9
Concrete w/c
0.70
Concrete: 28 day strength (MPa)
31.9
27.4
27.3
28.0
26.6
Concrete: RCPT (Coulombs)
6100
5800
6000
6400
6600
0.62
The RCPT values, reported in Table 3, are very high and imply that the chloride ion penetrability is
like to be high for the concrete tested. This according to Hamilton et al. (2007) is probably due to the
quality of the concrete used as is indicated by the high w/c ratios.
Matthews (1994) used the oxygen permeability method on concrete (w/c ratio = 0.60) made with
limestone cements that were manufactured by both intergrinding clinker and limestone and by
blending Portland cement and finely ground limestone. The results indicated that increasing the
limestone level decreased the oxygen permeability and that wet or dry curing conditions also
influenced the relative difference measured with the wet curing showing the bigger relative
difference. In addition Matthews also exposed reinforced concrete (w/c ratio = 0.60) specimens to a
marine environment for up to five years and found that the increased limestone level in cement did
affect the chloride penetration profile but not significantly. A far greater and positive effect was found
when using fly ash blended with cement.
The work by Bonavetti et al. (2000) supports the view expressed by Matthews (1994) that with wet
curing the chloride penetration of concrete increases in limestone cement concrete as compared to
Portland cement concrete, but that if air cured the opposite was found. The literature tends to indicate
that Portland limestone cement (PLC) concrete made with up to 15% limestone has similar resistance
to fluid penetration but that the chloride ion penetration is likely to be higher.
Research was carried out by Dhir et al. (2007) using the initial surface absorption test (ISAT) for
water absorption and the electrical migration test for chloride diffusion on five mixes with different
w/c ratios and made with Portland cement blended with finely ground limestone. The results indicated
that at limestone levels above 15%, the chloride diffusion and water absorption increased, but below
15% there was very little difference. However, when concretes of similar 28-day compressive
strengths were compared there was no significant difference, irrespective of the amount of limestone
used.
In work reported by Hooton, Ramezanianpour and Schutz (2010), using the ASTM C1556 chloride
bulk diffusion test method, indicated that the chloride diffusion coefficients did not change
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significantly. The concrete mixes used were made with Portland cement and limestone cements
containing limestone additions of 10% and 15% with and without GGBFS at 30% replacement levels.
This finding is supported by results reported by Thomas and Hooton (2010) where concrete made
with 12% limestone, containing 80% CaCO3, was compared to concrete with cement replaced by 35%
GGBFS and 20% fly ash respectively and tested for durability.
In summary, the research, both local and international, suggests that there is only minor or no
significant impact on the fresh and hardened properties of concrete made with limestone mineral
additions up to 15%. With respect to chloride ingress into concrete there appear to be differences of
opinion in the published data that, in my opinion, are related both to the differences in the concrete
mixes tested and the test methods used to determine the permeability of the concrete and the rate of
chloride ingress.
Discussion
The cementitious materials used in Australia are not dissimilar to those used in overseas countries
even though the National Standards are different. In the standards reviewed the requirements for both
the Type GP cements and the SCM are similar but not exactly the same. Again in the standards
reviewed the quality of the limestone allowed as a mineral addition is carefully controlled. Based on
this information it will be possible to compare the results obtained in the research with the published
data with confidence. However, with regard to the use of CKD in cement there was little or no
published data on the effect of this material on the cement or concrete properties.
The comparison of the Australian and international published data relating to the fresh and hardened
properties of concrete made with levels of limestone greater than 5% indicates that with correctly
proportioned mixes there are unlikely to be any significant problems.
Although the overall indication in the published literature suggests that with properly proportioned
mixes an increased limestone mineral (i.e. above 5%) does not significantly change the chloride
ingress into concrete (Thomas & Hooton 2010), the author is of the opinion that more information is
needed for Australian conditions. No specific information was found in the literature on the effect of
adding CKD to cement or on the subsequent effect on chloride ingress or the rate of chloride ingress
into concrete. This is a significant gap in the data and one that needs to be researched to provide
information to cement manufacturers, the concrete suppliers and the concrete specifiers in Australia
where the addition of this material is now permissible.
Conclusion and future research
Previous research also indicates that CKD can be added to cement (Daugherty and Funnell 1983).
However, there is a gap in the data relating to chloride ingress where CKD is added during the milling
of the clinker and in particular where the CKD contains chlorides. Similarly there is a gap in the data
relating to the effect of the including both higher limestone additions (greater than 7.5%) and CKD in
cement on the chloride ingress into concrete. There is some indication that without the inclusion of
SCM the durability of concrete may be at risk when increased levels of limestone mineral additions in
cement are used (Irassar et al. 2001). But, the literature in general appears to support the hypothesis
that that the use of SCM will improve the durability of the concrete (Thomas & Hooton 2010).
The following hypothesis will be investigated in the proposed research program.
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By increasing the level of limestone mineral addition and including kiln dust in cement, the chloride
ions may migrate more quickly through the matrix of the concrete. By replacing some of the cement
with supplementary cementitious materials, such as fly ash and ground granulated blastfurnace slag,
the rate of chloride ingress may be reduced to a level that will ensure long term durability of the
concrete.
The program will incorporate three different cements to make the mortar specimens, with water to
cement ratio (w/c) of 0.45. The cements will include, as the control cement, Type GP, with 5%
limestone but no CKD, and two experimental cements, containing CKD, at an amount to be
determined in preliminary testing, and limestone mineral addition at 10% and 15%. In addition to the
‘cement only’ mixes specimens will also be made with cement replaced by 20% and 30% fly ash and
30% and 50% GGBFS. The chloride ingress of these specimens will be determined by both a rapid
test method and by long term testing of specimens exposed to a standard sodium chloride solution for
up to three years. Concrete with a characteristic compressive strength of 40 MPa will also be tested to
confirm the findings of the mortar tests.
References
Adaska, WS, Taubert, DS 2008, Proceedings of IEEE/PCA 50th Cement Industry Technical
Conference: Beneficial uses of Cement Kiln Dust, Miami, Florida, pp 193-211.
Alunno-Rossetti, V and Curcio, F 1997, ‘A Contribution to the Knowledge of the Properties of
Portland-Limestone Cement Concretes, with Respect to the Requirements of European and Italian
Design Code’, Proceedings of the 10th International Congress on the Chemistry of Cement,
Gothenburg, Sweden, June 2-6, Ed. H. Justnes, vol.3, pp 26-32.
AASHTO 2002, ‘Standard Method of Test for Resistance of Concrete to Chloride ion Penetration’,
(ASSHTO T 259-2002), American Association of State Highway Transport Officials, Washington,
DC, USA.
ASTM 2005, Standard Specification for Portland Cement, (ASTM C 150-2005), American Society
for Testing and Materials, ASTM International, West Conshohocken, PA.
ASTM 2007, Standard Specification for Portland Cement, (ASTM C 150-2007), American Society
for Testing and Materials, ASTM International, West Conshohocken, PA.
ASTM 2004, Standard Test Method for Determining the Apparent Chloride Diffusion Coefficient of
Cementitious Mixtures by Bulk Diffusion, (AS 1556-2004), American Society for Testing and
Materials, ASTM International, West Conshohocken, PA.
ASTM 2007, Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride
Ion Penetration, (ASTM C 1202-2007), American Society for Testing and Materials, ASTM
International, West Conshohocken, PA.
ASTM 2011, Standard Test Method for Measurement of Rate of Absorption of Water by HydraulicCement Concretes, (ASTM C1585-2011), American Society for Testing and Materials, ASTM
International, West Conshohocken, PA.
Benn. BT. & Thomas. WA. 2012,’Properties of concrete made with cement containing increased
level of limestone addition: The Australian experience, Concrete in Australia, vol. 38 issue 1, Mar
2012, pp 20-26.
CMIC 12
21-9-2012
Page 12 of 27
Bhatty, MSY 1983, Use of Kiln Dust in Blended Cements, SN1717, Portland Cement Association,
Skokie, Illinois, USA.
Bhatty, MSY 1984a, ‘Use of Cement-Kiln Dust in Blended Cements’, World Cement Technology,
London, UK, vol. 15, no. 4, May 1984.
Bhatty, MSY 1984b, ‘Kiln Dust Cement Blends, Evaluated,’ Rock Products, Chicago, London,
Illinois, USA, vol. 88, no.10, October 1984.
Bhatty, MSY 1984c, ‘Use of Cement-Kiln Dust in Blended Cements: Alkali-Aggregate reaction
Expansion’, World Cement Technology, London, UK, vol. 16, no. 10, December 1984.
Bhatty, MSY 1986, ‘Properties of Blended Cement Made with Portland Cement, Cement Kiln Dust,
Fly Ash and Slag’, 8th International Congress on Chemistry of Cement, Rio de Janeiro, Brazil, Theme
3, vol. IV, no. 4, September 1986.
Bonavetti, V, Donza, H, Rahhal, V, Cabrera, O & Irassar, E. F 2000, ‘Influence of initial curing on
the properties of concrete containing limestone blended cement’, Cement and Concrete Research, vol.
30, no. 5, pp 703-708.
Bonavetti, V, Donza, H, Menéndez, G, Cabrera, O & Irassar, E. F 2003, ‘Limestone Filler in Low w/c
Concrete: A Rational Use of Energy’, Cement and Concrete Research, vol. 33, no. 6, pp 865-871.
British Standards Institution 1996, ‘Testing concrete, Recommendations for the determination of the
initial surface adsorption of concrete’, (BS 1881:208-1996), BSI, London.
Campiteli, VC, & Florindo, M 1990, ‘The influence of limestone additions on optimum sulfur trioxide
content in Portland cements’, Carbonate Additions to Cement, ASTM STP 1064, (eds P Klieger, &
RD Hooton), American Society for Testing and Materials, Philadelphia, pp 30-40.
Canadian Standards Association 1983, ‘Portland cement’, (CAN/CSA-A5, 1983), CSA, Mississauga,
Ontario, Canada.
Canadian Standards Association 2008, ‘Cementitious Materials for Use in Concrete’, (CAN/CSAA3001, 1983), CSA, Mississauga, Ontario, Canada.
Cement Concrete & Aggregates Australia 2009, Report, Chloride Resistance of Concrete, Cement
Concrete & Aggregates Australia (CCAA), Sydney, Australia.
Coal Combustion Products Handbook 2007, (eds. L Gurba, C Heidrich & C Ward), Cooperative
Research Centre for Coal in Sustainable Development, Australia, pp 202-205.
Day, KW 1999, Concrete Mix Design, Quality Control and Specification, 2nd (revised) edition, E &
FN Spon, London, England.
Daugherty, ED, & Funnel, JE 1983, ‘The Incorporation of Low Levels of By-Products in
Portland/Cement and the Effects on Cement Quality’, Cement, Concrete and Aggregates, American
Society for Testing and Materials, Philadelphia, Pennsylvania, USA, vol. 5, no.1 1983.
Dhir, RK, Limbachiya, MC, McCarthy, MJ, & Chaipanich, A 2007, ‘Evaluation of portland limestone
cements for used in concrete construction’, Materials and Structures, vol. 40, pp 459-473.
ENV 197-1: 1992, Cement – composition, specification and conformity criteria: Common cements,
European Committee for Standardization, Brussels, Belgium.
CMIC 12
21-9-2012
Page 13 of 27
EN 197-1: 2000, Cement – composition, specification and conformity criteria: Common cements,
European Committee for Standardization, Brussels, Belgium.
Fulton’s Concrete Technology 1994, (ed. BJ Addis), 7th (revised) edition, Portland Cement Institute,
Midrand, South Africa, pp 153-176.
Hamilton III, HR, Boyd, A & Vivas, E 2007, ‘Permeability of concrete – Comparison of Conductivity
and Diffusion Methods’, Florida Department of Transport Research Center, University of Florida,
Department of Civil and Coastal Engineering.
Heikal. M. El- Didamony. H. & Morsay. MS. 2000, Limestone - filled pozzolanic cement, Cement
and Concrete Research Vol. 30, pp 1827–1834.
Holderbank, 1999, By-Products of Clinker Burning: Kiln Dust and Stack Gas, Cement Seminar,
Materials Technology, Holderbank, Switzerland.
Hooton, RD, Nokken, M & Thomas, M.D.A 2007, ‘Portland-Limestone Cement: State-of-the-Art
Report and Gap Analysis for CSA A 3000, Report prepared for St. Lawrence Cement’, Cement
Association of Canada, Ottawa, Ontario, Canada.
Hooton, RD, Ramezanianpour, A, & Schutz, U2010, ‘Decreasing the Clinker Component in
Cementing Materials: Performance of Portland-Limestone Cements in Concrete in Combination with
SCM’s’, 2010 Concrete Sustainability Conference, National Ready Mixed Concrete Association,
Tempe, Arizona, USA.
Irassar, EF, Bonavetti, VL, Menhdez, G, Donza, H & Cabrera, O 2001, ‘Mechanical properties and
durability of concrete made with portland limestone cement’, Proceedings of 3rd CANMET/ACI
International Symposium on Sustainable Development of Concrete, ACI SP-202, American Concrete
Institute, Detroit, pp 431-450.
Matthews, JD 1994, ‘Performance of limestone filler cement concrete’, In Euro-Cements – Impact of
ENV 197 on Concrete Construction, (eds RK Dhir & MR Jones), E&FN Spon, London, pp 113-147.
Neville, AM 1995, Properties of Concrete, 4th Edition, Addison Wesley Longman Ltd, Harlow,
England.
NordTest, 1995, ‘Concrete, hardened: Accelerated chloride penetration’, (NT Build 443), Nordtest
method, Espoo, Finland.
NordTest, 1999, ‘Concrete, mortar and cement-based repair materials: Chloride Migration
Coefficient from Non-Steady-State Migration Experiments’, (NT Build 492), Nordtest method, Espoo,
Finland.
RTA 2001, ‘Interim test for the verification of curing regime - sorptivity’, (test method T362), Roads
and Traffic Authority of New South Wales, Sydney, Australia (now Roads and Marine Services of
NSW).
Schmidt, M 1992a, ‘Cement with interground additives – capabilities and environmental relief, Part
1’, Zement-Kalk-Gips, vol. 45, no 2, pp 64-69.
Schmidt, M 1992b, ‘Cement with interground additives – capabilities and environmental relief, Part
2’, Zement-Kalk-Gips, vol. 45, no 6, pp 396-301.
Schmidt, M, Harr, K & Boeing, R 1993, ‘Blended cement according to ENV 197 and experiences in
Germany’, Cement, Concrete and Aggregates, vol. 15 no. 2 pp 156-164.
CMIC 12
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Page 14 of 27
Soroka, I & Setter, N 1977, ‘The effect of fillers on strength of cement mortars’, Cement and
Concrete Research, vol. 7, no. 4, pp 449-456.
Sprung, VS, & Siebel, E 1991, ‘Assessment of the suitability of limestone for producing portland
limestone cement’, Zement-Kalk-Gips, vol.44, no 1, pp 1-11.
South African Bureau of Standards 1971, ‘Portland Cement (ordinary, rapid-hardening and sulphate
resisting)’, (SABS 471-1971, as amended 1973, 1981 & 1982), SABS, Pretoria, South Africa.
Standards Association of Australia 1991, Portland and blended cements, (AS 3972-1991), Standards
Australia, Sydney.
Standards Association of Australia 1997, Portland and blended cements, (AS 3972-1997), Standards
Australia, Sydney.
Standards Association of Australia 1999, Methods of testing concrete - Determination of water
absorption and apparent volume of permeable voids in hardened concrete, (AS 1012.21-1999),
Standards Australia, Sydney.
Standards Association of Australia 2010, General purpose and blended cements, (AS 3972-2010),
Standards Australia, Sydney.
Stanish, KD, Hooton, RD, & Thomas MDA 1997, Testing the Chloride Penetration Resistance of
Concrete: A Literature Review, Federal Highway Administration (FHWA), Contract DTFJ61-97-R00022, McLean, Virginia, USA.
Thomas, MD & Hooton, RD 2010, ‘The Durability of Concrete Produced with Portland-Limestone
Cement: Canadian Studies’, SN 3142, Portland Cement Association, Skokie, Illinois, USA.
Tsivilis, S, Chaniotakis, E, Badogiannis, E, Pahoulas, G & Ilias, A 1999a, ‘A study on the parameters
affecting the properties of portland limestone cements’, Cement and Concrete Composites, vol. 21 no.
2, pp 107-116.
Tsivilis, S, Chaniotakis, E, Batis, G, Meletiou, C, Kasselouri, V, Kakali, G, Sakellariou, A, Pavlakis,
G & Psimadas, S 1999b, ‘The effect of clinker and limestone quality on gas permeability, water
absorption and ore structure of limestone cement concrete’, Cement and Concrete Composites, vol. 21
no. 2, pp 139-146.
Tsivilis, S, Batis, G, Chaniotakis, E, Grigoriadis, Gr, & Theodossis, D 2000, ‘Properties and behavior
of limestone cement concrete and mortar’, Cement and Concrete Research, vol. 30 no. 10, pp 16791683.
Tsivilis, S, Chaniotakis, E, Kakli, G, & Batis, G 2002, ‘An analysis of the properties of portland
limestone cements and concrete’, Cement and Concrete Composites, vol. 24, pp 371-378.
Tsivilis, S, Kakli, G, Skaropoulou, A, Sharp, JH & Swamy, RN 2003, ‘Use of mineral admixtures to
prevent thaumasite formation in limestone cement mortar’, Cement and Concrete Composites, vol. 25,
no. 8 pp 969-976.
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accessed at: http://www.epa.gov/wastes/nonhaz/define/pdfs/cement-kiln-final.pdf.
Voglis, NG, Kakali, E, Chaniotakis, S, & Tsivilis, S 2005, ‘Portland-limestone cements. Their
properties and hydration compared to those of other composite cements’, Cement and Concrete
composites, vol. 27, pp 191-196.
CMIC 12
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Page 15 of 27
Appendix
CMIC 12 – Conference Presentation
CMIC 2012
Increased Limestone Mineral in Cement
the Effect on Chloride Ion Ingress of
Concrete – A Literature Review
B T (Tom) Benn – Adelaide Brighton Cement Ltd
Ass Prof Daksh Baweja – University of Technology Sydney
Prof Julie E Mills – University of South Australia
CMIC 2012
Mineral Additions & Chloride Ingress
•
•
•
•
•
•
•
•
Introduction
Background to mineral additions
Cements
Limestone
Cement kiln dust
Supplementary cementitious materials
General properties of concrete
Durability
Chloride ingress
•
•
CMIC 12
Transport mechanisms
Conclusions & Research proposal
21-9-2012
Page 16 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
•
Introduction
Limestone addition first used 1965
•
•
Heidelberg cement at 20%
5% mineral addition
•
•
•
•
•
•
Europe in general early 1980’s
South Africa 1982
Canada 1983
Australia 1991
USA 2005
Limestone cements (>5%) 1992 in ENV 197-1
CMIC 2012
Mineral Additions & Chloride Ingress
Comparison of cement properties
Property
Units
Standard
CEM I – 32.5
CEM I – 42.5
Type I
AS 3972
EN 197-1
EN 197-1
ASTM C150
≥ 45
≥ 75
≥ 75
≥ 45
Initial set
Minutes
Final set
Hours
<6
--
--
≤ 6.25
%
< 4.5
(clinker)
≤ 5.0
≤ 5.0
≤ 6.0
Chloride ion
%
≤ 0.10
≤ 0.10
≤ 0.10
--
SO3
%
≤3.5
≤ 3.5
≤ 3.5
≤ 3.0 (C3A < 8%)
≤ 3.5 (C3A > 8%)
≤ 3.0
MgO
CMIC 12
Type GP
Loss on ignition
%
--
≤ 5.0
≤ 5.0
Strength 2-day
MPa
--
--
≥ 10.0
--
Strength 3-day
MPa
--
--
--
12.0 (cubes)
Strength 7-day
MPa
≥ 35
≥ 16.0
--
19.0
Strength 28-day
MPa
≥ 45
≥ 32.5 ≤ 52.5
≥ 42.5 ≤ 62.5
28.0
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CMIC 2012
Mineral Additions & Chloride Ingress
Limestone
Australia & Europe
•
•
•
•
•
Natural inorganic mineral material
CaO3 not less than 75% by mass
If CaO3 between 75% & 80% must be tested:
•
Clay content must be less than 1.20% (methylene blue test)
•
Total organic test not greater 0.50% by mass
CaO3 content 80 % or greater no additional testing
Canada
•
•
CaO3 content at least 70% by mass
USA
•
•
CaO3 content at least 75% by mass
CMIC 2012
Mineral Additions & Chloride Ingress
•
Cement Kiln Dust
Dust created and extracted from kiln
•
•
•
Why removed
•
•
•
•
•
Causes build up and rings in kiln and preheater
Causes abnormal setting and strength characteristics in cement
If high in chlorides contributes to reinforcement corrosion
If high in alkalis contributes to ASR reaction
Chemistry
•
CMIC 12
Also known as by-pass dust
Typically between 7% – 15% of clinker
Similar to raw materials for cement and clinker
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Page 18 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Cement kiln dust chemistry
Constituent
Long dry kilns (U.S. EPA (1993) ABC data (07 – 10)
Silicon dioxide
4.3 – 10.1
9.5 – 20.6
Aluminium oxide
1.0 – 3.3
2.8 – 4.5
Iron oxide
0.7 – 2.3
1.8 – 3.1
Calcium oxide
11.0 – 45.0
41.5 – 62.9
Magnesium oxide
0.4 – 2.0
0.8 – 1.6
Sulphur trioxide
0.1 – 7.7
0.5 – 4.7
Chlorine
0.08 – 2.7
0.6 – 7.5
Potassium oxide
0.2 – 9.7
1.8 – 15.5
Sodium oxide
0.07 – 1.12
0.2 – 1.1
CMIC 2012
Mineral Additions & Chloride Ingress
•
•
Supplementary Cementitious Materials
Fly ash, ground granulated blastfurnace slag, silica fume
Advantages of using
•
•
•
•
•
•
•
•
•
CMIC 12
Improved workability
Better cohesiveness and pumpability
Improved post 28-day strengths
Reduction in ASR with reactive aggregates
Reduced shrinkage (fly ash)
Reduced heat of hydration
Lower permeability (important for resistance to chloride ingress)
Improved resistance to chemical (sulphate) attack
Protection of steel in marine environments (GGBS)
21-9-2012
Page 19 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Strength of concrete Made with Portland Cement & Portland limestone cement
(from Hooton & Thomas 2010)
No Water Reducing Admixture
PC-1
PLC-2
PC-2
With Water Reducing Admixture
PLC-4
PC-1
PLC-1
PLC-2
PLC-3
PC-2
PLC-4
Limestone, %
4.8
12
4.8
12
4.8
12
12
12
4.8
12
Blaine, m2/kg
380
500
380
500
380
450
500
580
380
500
0.502
w/c ratio
0.505
0.512
0.505
0.518
0.491
0.498
0.498
0.508
0.495
Slump, mm
115
110
115
110
110
110
110
80
105
105
1-day
19.2
21.4
18.5
18.9
21.8
21.9
23.6
24.6
21.0
22.0
7-day
33.5
32.7
32.3
31.6
35.3
34.4
35.2
36.7
35.6
35.0
28-day
41.1
39.8
39.3
39.9
42.2
40.3
41.9
42.5
42.3
41.5
56-day
43.8
43.3
44.0
43.0
45.2
43.6
44.7
46.6
45.2
45.8
CMIC 2012
Mineral Additions & Chloride Ingress
Compressive strengths of various grades of lab concrete (Benn & Thomas 2012)
CMIC 12
21-9-2012
Page 20 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Set times of various grades of lab concrete (Benn & Thomas 2012)
CMIC 2012
Mineral Additions & Chloride Ingress
Drying shrinkage of various grades of lab concrete (Benn & Thomas 2012)
CMIC 12
21-9-2012
Page 21 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Findings on properties in the literature
•
Voglis et al. (2005) - for similar compressive strength in concrete
•
limestone cement required a wider particle size distribution
Tsivilis et al. (1999a) – increasing tricalcium aluminate (C3A)
and reducing the tricalcium silicate (C3S)
increases compressive strength at all ages
irrespective of the limestone between 10% and 35%.
Bonavetti et al. (2003) - the increased early hydration and strength
due to formation of nucleation sites
Vogilis et al. (2005) - increased early hydration and strength
dueto the early formation of calcium carboaluminates.
•
•
•
•
•
•
•
CMIC 2012
Mineral Additions & Chloride Ingress
Findings on properties in the literature
•
•
•
•
•
CMIC 12
Matthews (1994) - for the same slump
(w/c) ratio needs to increase by 0.01 for limestone up to 5%
a further 0.01 when increased from 5% to 25%.
Schmidt (1993) - using cement from a different source,
reported water demand for concrete could be reduced
Hooton, Nokken & Thomas (2007) supported the statement
by Tsivilis et al. (1999a) ‘… that the appropriate choice of
clinker quality, limestone quality, percentage limestone
content and cement fineness can lead to the production of
a limestone cement with the desired properties’.
21-9-2012
Page 22 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Durability
Durability can be different things to different people such as:
• Not having to repair a structure for 20 years or more,
• Able to cope with changes in use,
• Able to cope with changes in loading,
• Able to resist chemical attack e.g. acids, alkali-silica reaction,
• Able to prevent chloride ingress to prevent corrosion of
reinforcement,
• Having a classical façade that does not seem to age with changes
in architectural fashions.
•
CMIC 2012
Mineral Additions & Chloride Ingress
Description of ingress mechanisms
•
•
•
•
CMIC 12
Diffusion – transfer free ions in the pore solution from high
concentration to low concentration regions.
Capillary absorption – when moisture encounters the dry surface of the
concrete, it will be drawn into the pores by capillary suction, this often
happens with wetting and drying cycles.
Evaporative transport (also called wicking) – similar to absorption but
where moisture, containing ions, is drawn from the wet surface through
the matrix to the dry surface.
Hydrostatic pressure or permeation – where the hydraulic pressure on
one side of the concrete forces the liquid, containing ions, into the
concrete matrix.
21-9-2012
Page 23 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Exposure
Type of structure
Primary chloride transport mode
Submerged
Substructure below low tide
Diffusion
Basement exterior walls or transport
tunnel liners below low tide. Liquid
containing structures
Permeation, diffusion and possibility
wick action
Tidal
Substructures and superstructures in
tidal one.
Capillary absorption and diffusion
Splash and
Superstructures about high tide in
the open sea.
Capillary absorption and diffusion
(also carbonation)
Land based structures in coastal area
or superstructures above high tide in
river estuary or body of water in
coastal area.
Capillary absorption (also
carbonation)
spray
Coastal
Mechanism of chloride transport (CCAA 2009)
CMIC 2012
Mineral Additions & Chloride Ingress
Findings reported in international literature
Property
Percentage limestone
0
10
15
20
35
Fineness (m2/kg)
260
340
366
470
530
Mortar: 28 day strength (MPa)
51.1
47.9
48.5
48.1
32.9
Concrete w/c
0.70
Concrete: 28 day strength (MPa)
31.9
27.4
27.3
28.0
26.6
Concrete: RCPT (Coulombs)
6100
5800
6000
6400
6600
0.62
Effect of limestone additions on the “chloride permeability’ of
concrete (Tsivilis et al. 2000)
CMIC 12
21-9-2012
Page 24 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Findings reported in international literature
Effect of Limestone Additions on Chloride Penetration of Concrete –
Oxygen Permeability (Matthews, 1994)
CMIC 2012
Mineral Additions & Chloride Ingress
Findings reported in international literature
Effect of Limestone Addition on the Chloride Diffusion
Coefficient of Concrete by Initial Surface Absorption
(Dhir et al. 2007)
CMIC 12
21-9-2012
Page 25 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Findings reported in international literature
Diffusion coefficients (x 10-12 m2/s) for concrete after 35 days
immersion in 3% NaCl solution (Hooton, Ramezanianpour & Schutz, 2010)
Cs (% mass)
GU
100%
PLC10
100%
PLC15
100%
GU 70%
GGBS 30%
PLC10 70%
GGBS 30%
PLC15 70%
GGBS 30%
0.73
0.84
0.8
1.1
1.07
0.98
Da (m2/s*1015.9
15.6
22.5
8.07
6.11
8.25
Notes:
(i) GU is general use Portland cement.
(ii) PLC is Portland limestone cement with either 10% or 15 % limestone.
(iii) The 70% implies 70 % cement and 30 % slag.
CMIC 2012
Mineral Additions & Chloride Ingress
Conclusions
•
•
•
•
•
CMIC 12
Some indication that without the inclusion of SCM the durability may be
at risk (Irassar et al. 2001).
Literature supports the hypothesis that that the use of SCM will improve
the durability even with high mineral additions(Thomas & Hooton 2010)
Previous research indicates that CKD can be added to cement
(Daugherty and Funnell 1983).
Gap in the data as no reference has been found relating to chloride
ingress where CKD is added during the milling of the clinker and in
particular where the CKD contains chlorides.
Gap in the knowledge on the effect of the inclusion of both higher
limestone additions and CKD in cement on the chloride ingress into
concrete, made with and without fly ash or slag.
21-9-2012
Page 26 of 27
CMIC 2012
Mineral Additions & Chloride Ingress
Proposed research
Mortar with w/c ratio ≈ 0.45 with following cementitious contents:
• Control - cement only mix, limestone additions = 5%, no CKD
• Experimental cement mixes, limestone additions = 10% & 15% + CKD.
• Cement/fly ash mixes, fly ash replacement = 20% & 30%.
• Cement/slag mixes, slag replacement = 30% and 50%.
• Measure compressive strengths development for up to three years.
• Measure chloride diffusion for up to three years (Nord Test NT 443 ?)
• Measure rapid chloride permeability (RCPT ASTM C 1202 ?)
Concrete with f’C of 40 MPa to confirm mortar findings
Research will support sustainability as suggested by the Kevin Gluskie
CMIC 12
21-9-2012
Page 27 of 27